ไฝฟ็จ readRDS() ๅฝๆธ่ผๅ
ฅ่ณๆ
NEI <- readRDS("~/Downloads/exdata_NEI_data/summarySCC_PM25.rds")
SCC <- readRDS("~/Downloads/exdata_NEI_data/Source_Classification_Code.rds")head(NEI)## fips SCC Pollutant Emissions type year
## 4 09001 10100401 PM25-PRI 15.714 POINT 1999
## 8 09001 10100404 PM25-PRI 234.178 POINT 1999
## 12 09001 10100501 PM25-PRI 0.128 POINT 1999
## 16 09001 10200401 PM25-PRI 2.036 POINT 1999
## 20 09001 10200504 PM25-PRI 0.388 POINT 1999
## 24 09001 10200602 PM25-PRI 1.490 POINT 1999
Have total emissions from PM2.5 decreased in the United States from 1999 to 2008? Make a plot showing the total PM2.5 emission from all sources for each of the years 1999, 2002, 2005, and 2008.
Have total emissions from PM2.5 decreased in the Baltimore City, Maryland(fips == '24510') from 1999 to 2008? Make a plot answering this question.
Of the four types of sources indicated by the type(point, nonpoint, onroad, nonroad) variable, which of these four sources have seen decreases in emissions from 1999โ2008 for Baltimore City? Which have seen increases in emissions from 1999โ2008? Make a plot answer this question.
Across the United States, how have emissions from coal combustion-related sources(SCC$EI.Sector) changed from 1999โ2008?
How have emissions from motor vehicle sources(SCC$EI.Sector) changed from 1999โ2008 in Baltimore City?
Compare emissions from motor vehicle sources in Baltimore City with emissions from motor vehicle sources in Los Angeles County, California(fips == '06037'). Which city has seen greater changes over time in motor vehicle emissions?